US 2832933 A
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April 29, 1958 c. L. GREENSLIT ET AL 2,832,933
WAVEGUIDE SWITCH Filed June 2, 1954 3 Sheets-Sheet l A IR 2 R. d
INVENTORS CHARLES L. GREENSLIT EDGAR G. SHELOR, JR.
April 29, 1958 c. GREENSLIT ET AL WAVEGUIDE SWITCH 3 Sheets-Sheet 2 Filed June 2, 1954 FIG. 3.
R v mm MEL E E ER H W6 8 ILG. ER R D A E H 0 G F ATTORNEYS.
April 29, 1958 c. GREENSLIT ETAL 2,832,933
WAVEGUIDE SWITCH Filed June 2, 1954 3 Sheets-Sheet 3 FIG. 5
INVENTORS CHARLES L. GREENSLIT EDGAR G, SHELOR,JR.
ATTORNEY-5' WAVEGUIDE SWITCH CharlesL. Greenslit and Edgar G. Shelor, Jr., Baltimore,
Md., assignors to Bendix Aviation Corporation, Towson,,Md., ,a corporation of Delaware This invention relates to'electric, switches and in particular, to waveguide switches.
Switches. of this general type have been invented, built and utilized in electronic devices designed'for signals whose frequencies are inthe microwave-range. Some of thefunctions for which these switches have been em ployed include switching between'antennas and switching betweendifferent pieces o'fapparatus-g Because ofthe necessity, of maintaining an, arrangement. that may -be easily operated, problems involving discontinuities and losses within the waveguides and leakage coupling between the waveguides have been prevalent. The present invention provides a means that substantially eliminates these problems.
An object of this invention is to provide a means for waveguide switching that introduces into the system a negligible amount of discontinuity caused by the necessity of providing rotatable joints within the means.
Another object of this invention is to provide a means for waveguide switching that is relatively non-critical with respect to the alignments in the rotatable joints of the waveguides within the means. I
Still another object of this invention is to vprovide a means for waveguide switching that is relatively noncritical with respect to spacing in the joints between the waveguides within the means.
A further object of this invention is to provide a means for waveguide switching such that a relatively low leak- 7 age of the signal occurs at the rotatable joints.
A still further object of this invention is to provide a means for waveguide switching that is compact and relatively economical to construct.
These and other objects are realized when referring to the figures where:
Fig. 1 is a sectional view of a pair of waveguides joined by a choke-flange joint;
Figs. 2a and 2b depict a portion of a waveguide switch which employs the choke-flange joint illustrated in Fig. 1;
Fig. 3 displays a portion of a waveguide switch employing a cylindrically curved surfaced choke-flange joint;
Fig. 4 is'a semi-sectional view of a portion ofv a waveguide switch employing the invention; and
Fig. 5 is a plan view of a switch employing the invention.
In joining two sections of a waveguide, a considerable amount of difliculty is encountered in providing a joint that does not introduce losses and reflections into the system. To circumvent the greater part of these problems, the so-called choke-flange joint is employed. Such a joint is illustrated in Fig. 1'. The extremities of the sections of the waveguides 1 and 2 shown in this view terminate in the flanges 3 and 4'respectively. 'The construction is such that the dimensions A and B of a cavity 5 formed by the flanges 3 and 4 are each equal to one quarter of the wavelength of the signal being conducted by the waveguides 1 and 2. Thevoltage and current values of the wave at an end 6 of the cavity 5 are zero discontinuities.
2,832,933 I-"ittentedii'Apr; 29, 1958 at the separation 7 and physical contact between the flanges 3 and 4 is not necessary. At an end 8 of the cavity 5, these characteristics will be the same. as at the end 6. Therefore, as the voltage is zero atthe end 8, the effect of a good connection betweenthe'waveguides land 2 has been produced withouta physical connection.
Choke-flange joints have'been used in the past in constructing waveguide switches, but losses, leakages and-discontinuities were produced-in-the system because of the clearance required in the process ofswitching.- This may be explained by referring to Figs. 2a and 2b, where a portion of a waveguide switch is displayed that employs 'the arrangement depicted in Fig. 1. Fig. 2a illustrates the necessity'of construction such that therewill be clearance at'a point 9 during the switching process, while Fig. 2b illustrates the increase in the separation 7 as a result of the clearance. It isthe increase in the separation 7 that produces the above mentioned losses, leakages and A: decrease in the separation 7 has been achieved in the past-by providing cylindrically curved surfaceson the endsof the flanges 3 and 4. The center-line about which the surfaces were generated corresponded to the center line about which the moving part of the switch rotated. This is illustrated in Fig. 3. It will be noted that in order to maintain a choke-flange joint, it is neces-' sary to provide a uniformity of depth below the separation 7 of the portions of the cavity 5 in the flange 4. This necessitates special machining processes.
The present invention provides a switch wherein the curvature of the surfaces of the flanges} and 4 is such that they are segments of spheres, the centers of which are coincident with the geometric center of the rotatable portion of the switch.
Referring to Fig. 4, there is shown a semi-sectional View of a portion of a waveguide switch that employs theinvention. As the surfaces of the flanges 3 and 4 are segments of spheres, a plane may be passed through either of the ends 6 and 8. Because of this, the full utilization of the choke-flange is accomplished in a switch that is economical to construct and lends itself to compact arrangements.
The complete benefits of the choke-flange joint are realized in that the joint presented to the waveguide lies in a plane perpendicular to the waveguide in coexistence with a minimum value of the separation 7. Because of the more efficient use of the choke-flange joint, the accuracy of the alignment of the waveguides and the uniformity of the separation 7 are less critical.
Although the radii forming the surfaces of the flanges 3 and 4 must maintain a relatively fixed relationship with respect to one another in order to minimize the separation 7, their absolute values may be varied while a true choke-flange joint is maintained. Therefore, the size of the switch is limited only by the other components thereof.
Because of the simplified design of the joint, it is easily manufactured. With the exception of the rectangular cutout in the center, the machining work may be per formed by simple operationson a lathe.
Fig. 5 illustrates a typical switch employing the invention.
The improved electrical operation of this type of a switch was evidenced in tests performed on a unit capable of switching between two inputs and two outputs. In these tests, only one input guide was used at any one time. It was found that through any of the R. F. paths, the VSWR was less than 1.15 and that the cross coupling attenuation was greater than db. 1 i
7. :1 ,saa,osa I t wanes particular embodiment of the present invention has been illustrated, it is to be understood that variations thereof are possible without departing from the scope of the invention.
What isclaimed is: a t V 1.. A switch of the waveguide type, comprising: a rotatable member; a plurality of terminal connectors of the waveguide type; said terminal connectors being evenly dispersedin a circle about the said rotatable member suchthat the surfaces of the innermost extremities of first sphere to provide clearance for the operation of the said choke-flange joints as such.
the said connectors lie, at the centers thereof, on thecirmember, with the center of the said circle coinciding with a point on the saidaxis; said extremities comprising half- .sections: of choke-flange joints; the surfaces ofsaid flanges having concave shapes that form segments of a sphere,
the radius of .which is equal to the radiusof the said circle and the center of which is'identical to thesaid center of the said circle; and a plurality of waveguides within the saidrotatable member; the extremities of the said waveguides being equal in number to the said connectors; the said extremities being; arranged'to coincide with the said connectors in certain angular positions of said rotatable member; the said extremities consisting of the mating half-sections of the said choke-flange joints; the surfaces of the said mating half-sections having convex shapes that form segments of a sphere, the radius of which issufiiciently less than the said radius of the said 2. In a switch of the waveguide type: selectively engageable choke-flange joints, each comprising a fixed and a movable component; said fixed and movable components having mating surfaces; said fixed components forming a group and said movable components forming another group; one of said group of components surrounding the other group of components; said mating surfaces of the said components of the said surrounding group having concave shapes that form segments of a sphere, the radius of which is equal to the shortest distance from the centers of the said surfaces to the axis of the said switch; saidsurfaces of the'said components of the said surrounded group having convex shapes that form segments of a sec'ond. sphere, the center of which is coincident with the center of the first said sphere, and the radius of which is sufficiently less than the said radius of the said fir st sphere to provide. clearance for the operation of the said choke-flange joints as such.
References Citedin the file of this patent UNITED STATES PATENTS 2,573,713 I Kannenberg Nov. 6, 1951 2,629,048 Dyke 4 Feb. 17, 1953 2,705,776 Starr Apr. 5, 1955 2,715,210 McClain Aug. 9, 1955 Drake Feb. 22, 1949